Comparison of single photon emission computed tomography findings in cases of healthy adults and solvent-exposed adults: correction of previous results.
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Adult↗
Biomedical subjects
T R Simon
Publications and source records attributed to T R Simon.
Homeless youth and their exposure to and involvement in violence while living on the streets.
PURPOSE: The purpose of this research were to explore homeless youths' histories of exposure to violence, perpetration of violence, and fear of violent victimization, and to examine the extent to which these constructs are associated with demographic variables. METHODS: A sample of 432 youth (between 13 and 23 years old) who were homeless or at imminent risk for homelessness were sampled from both service and street sites. The percentage of youth who reported exposure to each type of violence was calculated. Multiple regression analyses were used to examine differences in the risk of exposure to violence across gender, ethnicity, age, and length of time homeless. RESULTS: Respondents reported a high rate of exposure to violence. Female respondents reported levels of exposure to violence that were as high as those reported by males. Females were more likely to report having been sexually assaulted and fearing victimization, and tended to be less likely to report perpetrating violence. With a few exceptions, ethnic identity was not a significant predictor of exposure to violence or fear of victimization. Age tended to be inversely associated with risk of exposure to violence. Length of time homeless was not associated with fear of victimization. CONCLUSIONS: Homeless youth are at high risk for exposure to a variety of forms violence as both witnesses and victims. The overall rates of exposure to violence and patterns of association with demographic variables are significantly higher than those reported in national samples of adolescents.
Adolescent↗
Homeless youths and young adults in Los Angeles: prevalence of mental health problems and the relationship between mental health and substance abuse disorders.
Although understanding of the subsistence patterns, service utilization, and HIV-risk behaviors of homeless youths and young adults in increasing, relatively little is known about the epidemiology of mental health problems in this group or the relationships between mental health problems and substance use. This study measured symptoms of depression, low self-esteem, ADHD, suicidality, self-injurious behavior (SIB), and drug and alcohol use disorder in a sample of homeless youth and young adults living in Hollywood, CA. Results indicated extremely high prevalences of mental health problems as compared with corresponding rates of mental health problems found among housed youths in previous studies. Prevalence of mental health problems differed by age and ethnicity. African Americans were at lower risk of suicidal thoughts and SIB than were those of other ethnicities. Older respondents and females were at increased risk of depressive symptoms, and younger respondents were at increased risk of SIB. Previous history of sexual abuse and/or assault was associated with increased risk of suicidality and SIB. Risk factors for drug abuse disorders included ethnicity other than African American, homelessness for 1 year or more, suicidality, SIB, depressive symptoms, and low self-esteem. Risk factors for alcohol abuse disorder included male gender, white ethnicity, homelessness for 1 year or more, suicidality, and SIB. Extremely high rates of mental health problems and substance abuse disorders in this sample suggest the need for street-based and nontraditional mental health services targeted toward these youths and young adults.
Adolescent↗
Barrier durability of latex and vinyl medical gloves in clinical settings.
This study evaluated changes in the tensile strength and barrier integrity of medical gloves during hospital clinical use. Nonsterile vinyl, sterile vinyl, and nonsterile natural rubber latex gloves were collected after use in a clinical setting and then tested for tensile strength, elongation, and water leakage. Tensile properties of vinyl gloves did not change during use, whereas changes in latex depended on the brand evaluated. New gloves, regardless of material of manufacture, were found to have leakage rates of 2% or less. Two brands of nonsterile vinyl gloves were found to have an average rate of leakage after use of 24 to 28% (average 26%), three brands of latex gloves of 6 to 10% (average 8%), and one brand of sterile vinyl gloves of 3%. Low-protein powderless latex gloves leaked slightly less than the powdered brands. The high rates of leakage observed for nonsterile vinyl gloves indicate that they provide less barrier protection than latex in typical hospital use. The low leakage rate observed for sterile vinyl gloves indicates that barrier durability is not solely a function of the generic polymer composition of the barrier.
Equipment Failure↗
Intraventricular immunotoxin therapy for leptomeningeal neoplasia.
OBJECTIVE: The goals of this clinical trial of intraventricular 454A12-rRA therapy were to identify dose-limiting toxicities, to evaluate the pharmacokinetics of single-dose intraventricular 454A12-rRA, and to detect antitumor activity. METHODS: We performed a pilot study of intraventricular therapy with the immunotoxin 454A12-rRA in eight patients with leptomeningeal spread of systemic neoplasia. The immunotoxin 454A12-rRA is a conjugate of a monoclonal antibody against the human transferrin receptor and recombinant ricin A chain, the enzymatically active subunit of the protein toxin ricin. Patients were treated with single doses of 454A12-rRA ranging from 1.2 to 1200 micrograms. RESULTS: The early phase half-life of 454A12-rRA in ventricular cerebrospinal fluid (CSF) averaged 44 +/- 21 minutes, and the late phase half-life averaged 237 +/- 86 minutes. The clearance of the immunotoxin was faster than the clearance of coinjected technetium-99m-diethylenetriamine penta-acetic acid, averaging approximately 2.4-fold greater. No 454A12-rRA degradation was detected by Western blot analysis of ventricular CSF for a period of 24 hours, and bioactivity was retained in CSF paralleling the concentration of immunotoxin. No acute or chronic drug toxicity was identified in patients who received less than or equal to 38 micrograms of 454A12-rRA by intraventricular injection. Doses more than or equal to 120 micrograms caused a CSF inflammatory response that was associated with transient headache, vomiting, and altered mental status. This acute syndrome was responsive to steroids and CSF drainage. No systemic toxicity was detected. In four of the eight patients, a greater than 50% reduction of tumor cell counts in the lumbar CSF occurred within 5 to 7 days after the intraventricular dose of 454A12-rRA; however, no patient had their CSF cleared of tumor, and clinical or magnetic resonance imaging evidence of tumor progression was demonstrated in seven of the eight patients after treatment. CONCLUSION: Tumoricidal concentrations of the immunotoxin 454A12-rRA can be attained safely in the CSF of patients with leptomeningeal tumor spread.
Adult↗
Implementation and process evaluation of a student "school-as-community" group. A component of a school-based drug abuse prevention program.
Little documentation exists regarding the functioning of formalized adolescent groups as drug abuse prevention agents. Two studies are described that were conducted at high schools whose students are at high risk for drug abuse. Twenty-one schools were randomly assigned to one of three conditions: (a) standard care, (b) classroom drug abuse education only, or (c) classroom plus school-as-community. Results of the first study indicated that the school-as-community component--which involved weekly meetings and periodic events at seven schools--was implemented as planned, drug abused focused, and perceived as productive in discouraging drug abuse. In the second study, staff in the classroom plus school-as-community condition self-reported involvement in the greatest number of community activities across the school year, compared with staff from the other two conditions. These two studies support the feasibility of formalized groups of high-risk youth to promote drug-free events.
Adolescent↗
School-as-community activity selection at continuation high schools.
This paper describes two studies which together provide an example of an empirically based "school-as-community" development process used in a large-scale school-based drug prevention trial among youth at continuation high schools in California. First, we generated a list of schools' current community involvement from 96 school personnel and 144 students from 20 continuation high schools. Second, we reduced the number of activities indicated, with some discussion, to a list of 12 populars. Then, we administered this list to a total of 388 students from six continuation high schools who provided perceived quality ratings. We generated six categories of activities from the results of these two studies. These studies reveal a means to determine activities likely to be completed by this school system and a means to limit the variability of activities which could be manipulated in an experimental trial involving a school-as-community component.
Adolescent↗
Immediate impact of thirty-two drug use prevention activities among students at continuation high schools.
Those teenagers who are unable to remain in the regular school system for reasons including substance use are transferred to a continuation high school. Generic comprehensive social-influence-drug-use-prevention-activities are less likely to be effective for use with these at risk youth. Thus, both classroom and self-instruction (main mode of instruction at continuation high schools) versions of 16 activities derived from different theoretical sources were tested and ranked on immediate outcome variables. 388 students from six continuation high schools were provided with a pretest-activity-posttest "component study" protocol. The scores on perceived quality ratings were standardized and averaged to permit easy comparisons across lessons. While yielding similar knowledge changes, students who received the health educator led activity consistently reported higher scores on perceived quality. Social influence-oriented lessons, in general, were rated of relatively low perceived quality. The present approach assisted in selection of the lessons with the greatest overall immediate impact.
Adolescent↗
"Substance abuse" disorders among runaway and homeless youth.
This study used systematic sampling methods to recruit a sample of 432 homeless youth from both service and natural "hang-out" sampling sites. According to DSM-III criteria, the majority of respondents were classified as having an alcohol and/or illicit "drug abuse" disorder (71%). The results from multivariate logistic regression analyses indicate that cumulative length of time homeless is positively associated with risk for an "abuse" disorder. The implications of these findings and recommendations for service interventions are discussed.
Adolescent↗
Vulnerability to victimization, concurrent problem behaviors, and peer influence as predictors of in-school weapon carrying among high school students.
Previous research has indicated the potential relevance of three constructs in the prediction of adolescent weapon carrying, (a) general delinquency, (b) self-protection, and (c) social influence. The current study tests the independent associations between in-school weapon carrying and these three constructs. The sample consisted of 504 students from seven southern California high schools. Overall, 25% of the sample carried a weapon to school in the last year. Self-defense was the most commonly reported reason for in-school weapon carrying. The results from a simultaneous logistic regression analysis indicated increased risk of in-school weapon carrying among students who are male, who are affiliated with gangs or tagging crews, who are exposed to peers who carry weapons to school, and who feel vulnerable to being victimized. Prevention programs targeted at reducing in-school weapon carrying may benefit from a comprehensive focus that includes efforts to reduce involvement in other problem behaviors, influence norms regarding weapon carrying, and reduce actual and perceived vulnerability to victimization.
Adolescent↗
Predictors of misreporting cigarette smoking initiation among adolescents.
This study examines the prevalence of invalid reports of cigarette smoking initiation among adolescents (i.e., reporting cigarette smoking at one time point and denying ever trying cigarettes at a subsequent time point) and the association of misreports with scores on other problem-prone variables. Misreports did not vary as a function of item complexity and did not reflect careless responding. In the seventh grade, misreporters' scores on the problem-prone variables were higher than those of nonsmokers and lower than those of smokers. In contrast, when measured in the eighth grade, misreporters' scores did not differ from those of nonsmokers. Misreporters did show a greater decrease in intentions to smoke, alcohol use, and number of friends who smoke compared to nonsmokers and consistent smokers. Explanations for these findings are discussed.
Adolescent↗
Continuation high schools: youth at risk for drug abuse.
Students at alternative high schools may be at substantial risk for drug abuse. The present article provides a general overview of the drug use-related context of continuation high schools in southern California. A total of 144 students and ninety-six staff were interviewed from twenty continuation high schools. The interview data revealed that continuation school students show high levels of substance use. However, only 20 percent of the students report that they received any drug abuse prevention programming. Also, students at continuation high schools aspired to a productive life after high school including continued education. Thus, these youth may still be amenable to preventive educational interventions which deter them from drug use and help them to fulfill their future goals.
Adolescent↗
Kinetic analysis of rat parotid gland muscarinic receptors in vivo: comparison with brain and heart.
(RR)- and (SS)-quinuclidinyl iodobenzilate enantiomers [(RR)- and (SS)-IQNB, active and inert, respectively] have been synthesized for quantitative evaluation of muscarinic acetylcholine receptor (mAChR) binding. Pharmacokinetic approaches have not been used previously to assess in vivo IQNB binding in nonexcitable tissues. We have applied this method to examine mAChRs in rat parotid gland in comparison to those in brain and heart. Short-term infusion studies in vivo showed that the "instantaneous" reversible binding of (RR)- and (SS)-IQNB was high in the parotid (greater nonspecific binding potential), intermediate in the heart, and lowest in cortex and cerebellum. Long-term bolus injection experiments showed that the parotid gland mAChRs possessed a binding potential for receptor specific sites (380), which was intermediate between that of parietal cortex (930) and cerebellum (10) and greater than that of heart (165). In vitro binding to plasma membranes was generally consistent with the in vivo findings. In aggregate, these studies show that mAChRs can be evaluated in vivo in a nonexcitable tissue with the use of stereospecific ligands and a pharmacokinetic approach. The data suggest that IQNB, a mAChR antagonist, can identify characteristics of specific binding sites, which may reflect tissue differences.
Animals↗
Project towards no tobacco use: 1-year behavior outcomes.
OBJECTIVES: We present 1-year follow-up data from a school-based tobacco use prevention project designed to test the effectiveness of three main components of social influence programs. The components teach refusal skills, awareness of social misperceptions about tobacco use, and misconceptions about physical consequences. METHODS: Four different curricula were developed and tested in a randomized experiment involving 48 junior high schools. The outcome variables examined were changes in initial and weekly cigarette and smokeless tobacco use 1 year after the intervention. RESULTS: Analyses indicated that each of the component programs were effective in decreasing both the initial and the weekly use of cigarettes except for the curriculum in which refusal skills were taught. Also, each curriculum was effective in decreasing the initial use of smokeless tobacco except for the one aimed at correcting social misperceptions. Only the combined curriculum showed an effect on the weekly use of smokeless tobacco. CONCLUSIONS: The combined intervention was the most effective overall in reducing the initial and weekly use of cigarettes and smokeless tobacco. This suggests that different reasons for use exist and need to be counteracted simultaneously. However, since single programs were also effective in reducing all but weekly smokeless tobacco use, any of these components may be worthwhile prevention tools.
Adolescent↗
Analysis of thallium-201 single-photon emission computed tomography after intravenous dipyridamole using different quantitative measures of coronary stenosis severity and receiver operator characteristic curves.
The presence of significant coronary artery disease in individual vessels was assessed using thallium-201 single-photon emission computed tomography (SPECT) after intravenous dipyridamole. Coronary angiograms were analyzed using quantitative computer-assisted techniques in 81 men patients. Eleven men with a less than 3% probability of coronary artery disease were used as a control population. Three definitions of a hemodynamically significant coronary stenosis were studied independently: (1) a greater than 50% luminal diameter narrowing; (2) an absolute cross-sectional area less than or equal to 2.0 mm2; or (3) a greater than or equal to 70% cross-sectional area obstruction. Myocardial perfusion after dipyridamole was analyzed using the quantitative (polar map) method in 213 regions from the group with known coronary anatomy and using 33 regions from the group with a low likelihood of disease. Receiver operating characteristic curves were used to define the best cut-off point for the discrimination between normal and abnormal perfusion. When related to each of the three quantitative angiographic criteria, the optimum balance between sensitivity and specificity occurred at a defect size of greater than or equal to 8% for the left anterior descending artery, greater than or equal to 4% for the circumflex artery, and greater than 0% for the right coronary artery. Using a luminal diameter narrowing of greater than 50% to define the presence of significant coronary artery disease, these corresponded to respective sensitivities and specificities of 0.82 and 0.76 for the left anterior descending artery, 0.71 and 0.71 for the circumflex artery, and 0.76 and 0.82 for the right coronary artery. Thus analysis of receiver operator characteristic curves provides a means to define abnormalities for the SPECT polar map program after dipyridamole stress. Different definitions of coronary stenosis significance as determined by quantitative angiography did not substantially alter the results of the thallium imaging data and thus suggest that these definitions are functionally similar.
Coronary Disease↗
Demineralized perforated bone implants in craniofacial surgery.
Between July 1990 and September 1991, demineralized perforated allogeneic bone implants (Pacific Coast Tissue Bank, Los Angeles, CA) were placed in 72 patients. Because many patients received more than one implant, a total of 248 implants were used in 80 procedures. The technology of processing demineralized bone implants is described in detail. All patients were operated on by one surgeon (K.E.S.) at the Humana Craniofacial Institute in Dallas, Texas. Forty-one patients had craniofacial deformities, 16 had secondary deformities following cleft lip and palate repair, 8 had bony defects following removal of tumors, and 10 had various skeletal deformities following trauma. Of the 72 patients, 6 had two surgical procedures during which additional implants were inserted. Implants placed in the cranial vault and the maxillary complex, including alveolar grafts, were inlay grafts, whereas implants placed in the orbital, nasal, paranasal, temporal, and malar areas were onlay grafts used for contouring, augmentation, or both. Complications were limited to delayed wound healing in 6 patients. According to our observations, demineralized perforated bone implants represent an encouraging alternative to autogenous bone grafting. Further clinical and experimental studies are necessary to obtain more information about this material.
Adolescent↗
Hypoxia and cyanosis in alpha-1-antitrypsin deficiency. Cirrhosis as an unusual etiologic factor.
A patient with type PiZZ alpha-1-antitrypsin deficiency was found to have severe hypoxia despite normal pulmonary function testing and a normal chest radiograph. A nuclear medicine ventilation-perfusion study revealed a right-to-left shunt. Computed tomography showed minimal bleb formation, no diffuse changes, and hepatic changes of cirrhosis with portal hypertension. No nodular pulmonary masses or enlarged peripheral pulmonary vessels were found. The diagnosis of diffuse intrapulmonic arteriovenous shunts ("pulmonary spiders of cirrhosis") was suggested and then confirmed with a dynamic radionuclide flow study.
Cyanosis↗
Reverse redistribution of thallium-201 detected by SPECT imaging after dipyridamole in angina pectoris.
Reverse redistribution refers to a thallium-201 perfusion defect that develops or becomes more evident on delayed imaging compared with the initial image immediately after stress. To determine the diagnostic importance of reverse redistribution after intravenous dipyridamole, thallium-201 single photon emission computed tomography and quantitative coronary arteriography were performed in 90 men with angina pectoris. Of the 250 myocardial segments analyzed, reverse redistribution was present in 17 (7%). Minimal coronary cross-sectional area in proximal vessel segments was less than or equal to 2.0 mm2 more often in regions with transient perfusion abnormalities than in regions with reverse redistribution (66 vs 29%, p less than 0.05). Compared with regions exhibiting transient perfusion abnormalities, regions with reverse redistribution had larger proximal arterial diameters (1.9 +/- 1.1 vs 1.3 +/- 1.1 mm, p less than 0.001) and cross-sectional areas (3.9 +/- 3.1 vs 2.2 +/- 2.6 mm2, p less than 0.001). Coronary artery dimensions and relative stenosis severity did not differ between those regions with normal perfusion and those with reverse redistribution. Reverse redistribution detected by thallium-201 single photon emission computed tomographic imaging after dipyridamole is uncommon, appears to occur as frequently in normal subjects as in patients undergoing coronary arteriography and does not indicate the presence of severe coronary artery disease.
Adult↗